Micrometer for circular size, especially of grooves



J. T. GONDEK May 25, y1954 MICROMETER FOR CIRCULAR SIZE, ESPECIALLY OF GROOVES Filed June 19, 1950 Patented May 25, 1954 MICROMETER FOR CIRCULAR SIZE, ESPECIALLY F GROOVES .lohn T. Gondek, Minneapolis, Minn., assigner to Northern Pump Company,

Minneapolis, Minn.,

a corporation of Minnesota Application June 19, 1950, Serial No. 169,014

(Cl. Sii-178) 3 Claims.

This invention relates to a micrometer structure and particularly to a micrometer for measuring cylindrical surfaces such as the walls of bores. There are at present micrometers on the market which are constructed for measuring concave cylindrical surfaces. Such micrometers comprise radially movable pins adapted to engage such cylindrical surfaces. Said pins however have a very small amount of radial movement and are not suitable for measuring depressions such as grooves on the surfaces of cylindrical bores.

It is an object of this invention to provide a micrometer having radially movable pins which are guided in apertures in a casing and are arranged for quite a long range of movement.

It is another object of the invention to provide a micrometer structure comprising a substantially cylindrical casing having a plurality of circumferentially spaced apertures therethrough, a plurality of radially movable pins disposed respectively in said apertures and a member in said casing movable longitudinally thereof having a plurality of Vcircumferentially spaced portions having outer surfaces inclined atan angle to the ,radii of said pins respectively, said pins having slots in their inner ends receiving said portions, the bottoms of said slots respectively engaging said surfaces, said pins being adapted to be moved outwardly by longitudinal movement of said member.

It is also an object of the invention to provide such a structure as set forth in the preceding paragraph, together with resilient means urging said pins inwardly. Y

It is still another object of the invention to provide Va micrometer structure comprising a casing of general cylindrical form having a plurality of circumierentially spaced apertures therethrough, the axes of which extend radially respectively of said casing, a plurality of pins movable in said apertures respectively, a member in said casing having circumferentially spaced radial slots therein, and a member having a plurality of circumferentially spaced radially extending ribs disposed respectively in said slots, said pins engaging said ribs, and being moved outwardly by said ribs, said pins having outer terminal portions of reduced diameter, the outer surfaces of which are preferably semi-cylindrical in form.

It is more specifically an object of the invention to provide a micrometer structure comprising ak casing of general cylindricaliorm having a plurality of circumferentially spacedholes therethrough and having circumferentially spaced slots extending longitudinally thereof, a plurality of pins iitting in and movable in said holes respectively, said pins being disposed radially of said casing, a member for moving said pins outwardly having circumferentially spaced ribs with outer sides disposed at an angle to the radii of said pins respectively, said ribs being movable in said slots, the inner ends of said pins having interlitting engagement with said ribs, the inner ends of said pins preferably having slots therein, the bottoms of which engage the outer surfaces of said ribs, together with means for. moving said pins inwardly.

These and other objects and advantages of the invention will be fully set forth in the following description made in connection with the accompanying drawings in which like reference characters refer to similar parts throughout the several views and in which:

Fig. l is a view ci the device mostly in central longitudinal section and partly in side elevation, also showing a member to be measured;

Fig. 2 is a view similar to Fig. i showing the parts in dilerent positions;

Fig. 3 is a vertical section taken on line 3-3 of Fig. 2, as indicated by the arrows;

Y Fig. d is a partial view showing one end of one o the pins used;

Fig. 5 is a view similaito Fig. 4, as seen from the right of Fig. 4;

Fig. 6 is a partial view in side elevation showing one use of the device in a member shown in central vertical section;

Fig. 7 is a vertical section taken on lineV l--i of Fig. l and shown on a reduced scale; and

Fig. 8 is a partial view similar to Fig. 6 shown on an enlarged scale.

Referring to the drawing, a micrometer structure is shown comprising a casing l0. Casing lo is preferably of general cylindrical form and has an enlarged interiorly threaded end portion ita. Member is is also interiorly threaded at its other end portion ith, said latter portion being shown as of somewhat increased exterior diameter. A member li is provided having a central annular portion Ila and reduced exteriorly threaded end portions Hb and Hc. End portion lib is threaded into the end of portion ita, the end of portion Illa, engaging portion tia. An end member i2 has an enlarged intericrly threaded end portion which is threaded on portion i ic and the end of which engages portion lia. Member l2 is closed at its other end. Member l l is provided in its portion Ha with a plurality of circumferentially spaced apertures, bores or holes Hd and while these might be variously formed, they are preferably cylindrical. In the embodiment of the invention illustrated, four of these holes are shown, opposite pairs being coaxial with the axes of said pairs disposed at right angles. Member il is also provided with circumferentially spaced slots He equal in number to the number of holes iid, which slots extend longi tudinally of member i l and the axes of holes iid lie in the central planes of slots He. Member li is shown as having circumferentiallyA spaced longitudinally extending holes Hf, for reducing the weight of member il. Pins i3 nt in and movable respectively in the holes Hd. Whilev these pins could be variously formed, in the embodiment of the invention illustrated they are shown as having terminal ribs i3d at their outer ends which extend thereacross, said ribs having their outer ends of semi-circular form in crossV section. A member of cylindrical rod-like form is provided which has extending therefrom adjacent one end a pluralityof circumferentially spaced iiat ribs isa disposed at right angles to each other and disposed in and movable in the slots He oi member il. As shown in Figs. l and 2, the rear ends of ribs ida extend substantially at right angles to the axis of member iii while the outer sides of said ribs for most of their length have outer flat surfaces disposed at an acute angle to the axis ci member ill and to the axes of the pins iii. Said ribs have iront portions ill?) extending substantially parallel to the axis of member id. Member i@ is disposed coaxially of casing is and is longitudinally movable in casing is and in member ii, inember having a slightly enlarged rear portion lilo which is slidable in a sleeve il secured in casing i6. The end portion ci member iii nts in and is held in a member iii which is provided with a cylindrical portion 'fitting in and slidable in the bore iic in one end of casing iii. The pins i3 have interiitting engagement with the ribs idc, the pins being shown as having slots at their inner ends having parallel sides and a bottom at right angles thereto, as clearly shown in Fig. 3. Said slots have bottoms extending at an angle to the radii respectively of pins i3, said bottoms engaging and riding on the inclined outer sides of ribs lila.. Ribs isa. are substantially rectangular in radial section, as clearly shown in Figs. 3 and 7. The angle said bottoms make with the axes of said pins is substantially equal to the angle which the inclined sides of the ribs malte with the axes of said pins. rthe pairs of pins on opposite sides of casing lo have transverse slots adjacent their inner ends in which are disposed the ends of bow spring members s disposed at right angles to each other. Members 2s are disposed in members ii and i2, one of them having its bight portion disposed inwardly of the other and engaging said other, the other spring engaging a lug projecting inwardly from the closed end of member i2. Springs 2@ are widest at their midportions and taper in width toward their ends, the end portions thereof having parallel sides, It will be seen that springs 2e tend to move pins i3 inwardly.

Member i5 has a small central projection Ida which is engaged by one end of a screw 22 which is threaded into a member 255 in turn threaded into portion ich ci casing it. Member 23 has an enlarged portion knurled on its outer surface which is in substantial engagement with 4 the end of member li). Member 23 has an outer smooth cylindrical portion on which a member 2b ts and is rotatable. Screw 22 is secured at its outer end to member 25 by being threaded therein. rEhe smooth portion of member is provided with graduations 2317 spaced longitudinally thereof and which are appropriately numered. The inner endiof member 25 is beveled and its beveled surface is provided with circumferentially spaced graduations 25a adapted to cooperate with graduations 23h and with a longitudinal line extending longitudinally of member The graduations 25a are appropriately numbered.

In operation, when it is desired to measure the interior of a bore or a concave cylindrical sur face, member 25 will be rotated and this will move screw 22 longitudinally. Screw 22 engage member is and member is together with member iii is moved longitudinally of casing lil. The cuter surfaces of ribs 14a engage the bottoms of the slots in pins i3 and said pins are moved outwardly until their terminals engage the surface to be measured. The ribs Ilia and thus member is are guided by the slots in the ends of pins i3. The dimension can then be read on the graduations 23h and 25d. When member 25 is rotated in the opposite direction, member 22 will be moved toward member 23 Land-the springs will then move the pins'i3 inwardly as permitted by the ribs ifia. It is now common to have annular grooves in bores such as shown by the grooves Esc in the member 23. Such grooves arel commonly used to receive O-rings now used in large numbers for sealing purposes or to receivesnap ring fasteners. known in the art and are shown in U. S. Patent No. 2,394,364. The portions i3d on the pins i3 are very well suited for measuring the diameter of the grooves 23a, as shown in Fig. 2. In some cases the grooves are narrow so that only portions i3d can enter the same. l't is common to have grooves, such as shown at 23h in member 28, as shown in Fig. 2, which grooves 2% are of trapezoidal form in cross section. rihese grooves have to be very accurately made and it hasheretofore been difficult to accurately locate and finish the same. With the present mircrometer the inclined side of the groove can be engagedby the semi-circular surface on portions 43a, as shown in Figs. 6 and 8, and the inclined side can thus be nished to properly receive a snap ring which has an inclined side engaging the inclinedside of the groove. The endof member iii will be placed in contact with one end of the bore 2li, as shown in Fig. 6. The proper linishing of the groove is made much easier since fewer dimensions are necessary. rThe semicircular surface of the portions i3d( will engage the inclined side or" the groove at a point equal to the diameter of the sealing ring. rihel angle of the inclined side of the groove is known and the diameter of the semi-circular surface on portion i3d is known as is the distance of the pins i3 from the end of bores?,` so that the inclined side can thus be accurately measured and finished.

The disclosed structure of micrometer has several advantages over the standard structures now on the market. The pins i3 are engaged at spaced points. They are held at their inner ends by the engagement oi the` grooves therein with the ribs 14a andv are guided accurately in the holes in casing lla. With the described Vstruc- O-rings are now well ture a large range of movement is possible for the pins I3. In the present standard micrometers the range of movement is very small. The bores or holes Hd have considerable length and a long bearing surface isprovided for pins I3 which results in great accuracy.

From the above description it will be seen that I have provided a novel structure of micrometer and one which performs new functions and attains new results. The structure is comparatively simple and is easily operated. The device has been amply demonstrated in actual practice and found to be very successful and efficient.

It will of course be understood that various changes may be made in the form, details, arrangement and proportions or the parts, without departing from the scope of applicants invention, which generally stated, consists in a device capable of carrying out the objects above set forth, in the parts and combinations of parts disclosed and defined in the appended claims.

What is claimed is:

1. A micrometer structure having in combination, a casing having a central longitudinal axis and three or more substantially equally and circumferentially spaced apertures extending radially therethrough, a cylindrical pin fitting in and movable radially of said casing in each of said apertures, each of said pins having a groove in its inner end extending transversely thereof, a Wedge member having circumferentially spaced ribs with iiat outer surfaces extending at an acute angle to said axis, said ribs fitting in said grooves in the bottoms of said pins respectively, said ribs being slidable in said grooves so that the bottoms of said grooves bear on said outer surfaces of said ribs and the sides of said grooves engage the sides of said`ribs, means for moving said wedge member longitudinally of said axis, and resilient means for moving said pins inwardly and holding the same against said ribs.

'2. The structure set forth in claim 1, said casing being substantially cylindrical in form and having a closed chamber therein extending in front of and enclosing said wedge member.

3. A micrometer structure having in combinaa easing of general cylindrical form thus having a central longitudinal axis, said casing having four circumierentially and substantially equally spaced cylindrical apertures extending radially therethrough, a cylindrical pin movable radially in and fitting in each of said apertures, said pins being disposed and movable solely in said casing, a member movable in said casing longitudinally thereof having four circumferentially and substantially equally spaced ribs with flat outer sides inclined at an acute angle to said axis, said ribs having sides at right angles to said outer sides, the inner ends of said pins having slots in the bottoms thereof shaped to fit over said ribs with the bottoms of said slots bearing on said outer surfaces of said ribs, means foi' moving said member longitudinally of said casing, and resilient means engaging said pins for moving the same inwardly, said pins having narrow ribs extending from their outer ends centrally thereof having outer convex surfaces whereby said last mentioned ribs can engage circumierentially spaced points of a cylindrical surface.

References Cited in the le of this patent UNITED STATES PATENTS 

